Molecular identification of avian infectious bronchitis virus serotypes of broiler chicken in Gilan province

Infectious bronchitis virus (IBV) is the prototype of the family Coronaviridae, which is the causative agent of infectious bronchitis (IB). This disease is highly contagious, which causes massive damages to the poultry industry. This study aimed to investigate the prevalence of IBV serotypes of broiler chicken in Gilan Province.

This cross-sectional study was carried out on trachea and lung tissue samples collected from 50 broiler chicken flocks in Gilan province. First, the IBV positive samples were identified by RT-PCR. Thereafter, The serotypes of these isolates was determined by Nested-PCR reaction specified for Massachusetts and B/793 serotypes.

Overall 32 out of 50 (64%) poultry chicken flocks were infected to IBV. Specific nested PCR on IBV positive RT-PCR products revealed that 10 (31.25%) of IBV positive samples were infected by 793/B type and 22 (68.75) were identified as Massachusetts type.

Massachusetts type vaccines such as H120 are only partially effective against other serotypes of virus. Because of the presence of 793/B type of virus in Gilan poultry farms, the addition of this strain in combination with Massachusetts strain seems necessary to stimulate better protective immunity.